Poland and Estonia are close to Russia. Greece has her own worries about Turkey...

Greece was nearly bankrupt saved an EU bailout, mostly financed by German banks. Yet the Greeks spend more on the military in 2015 than many EU nations. Not sure as a result of Turkey as much as personnel costs and domestic instability.

Poland has pledged to increase military spending to meet the NATO 2℅ threshold in 2016 as a result of Russian aggressiveness in the region.

Estonia, although has seen a sharp decline in military spending per GDP remained in 2015 above the NATO threshold.

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Any domestic instability in Greece is not the job of the defense ministry (yet). The increased defense spending is indeed because of Turkey, although it is a small fraction that was before (more than 6% on a significantly increased GDP). You have to remember that Greece has the largest tank fleet and the second largest air force in the EU, a significant navy and all these on top of a significant number of active personnel, and these things cost money to maintain, as well as to train personnel on them.

For Poland and Estonia the reason is obvious, any potential Russian aggression.